1. Field of the Invention
The invention relates to a control method to make IC's operation mode to be provided with uncertainty, particularly to the usage of a long serial number which is produced from two sets of random numbers to serve as control signal of IC's behavior, wherein ways of control vary with the variation of the random numbers, thus the design of IC's operation mode can be provided with uncertainty.
2. Description of the Prior Art
Whereas, as the global has gradually developed towards computerization and digitalization, many commercial behaviors have translated into application of information technology, enjoying the efficiency, convenience and business opportunity brought by Internet and Intranet. Almost everyone holds a credit card, and IC cards for gate restriction, ID verification, system setup and shutdown, in which are normally stored with such extremely confidential information as personal data, password, or service priority, etc. and not intended to be shown to others (including the holder). In general, the IC cards which are obtained either due to personal or positional reason, and absolutely most of those who own the cards should take good care of them and reserve them due to either ethical reason or personality cultivation. However, due to the process of digital formalization of these data into digital data flow, such as 0, 1, after an IC card has been inserted into a card reader, it shall be read by the card reader and transferred to a system for verification or password check. During the process, the IC card's identification code may be caught in the first timing, the password be caught in the second timing, and the password be caught to perform data encoding/decoding operation in the third timing. Those operation procedures remain unchanged in the card reader. In other words, once the sequence flow of the operation of the card reader is known, through observation method (observing the changes of IC voltage and current), a hacker may analyze the difference of each IC card and figure out the key of the card reader. No matter whatever encoding manner the IC card's data are produced, the data stored in it could be fully exposed externally, not to mention the security.
Moreover, assuming IC catches data with different delay time; for example, delays for 800 clock to catch the identification code, delays for 1200 clock to catch the password, delays for 1000 clock to process data encryption/decryption, so as to mix up the reading sequence of IC, yet its mean delay value is 1000 clock. Owing to the delay operation is produced in real random manner, to a person skilled in the art, the characteristics of IC operation can be solved through more mean tests to get its mean value, thus IC still can't be protected thoroughly.
Therefore, if we can make IC's behavior mode to be provided with uncertainty, that is the mean delay value produced in each IC processing is different, then a hacker can hardly observe the IC's characteristics through observation method or conducting mean test. Even if a hacker is lucky enough to calculate the correct timing point, but it is still impossible to apply this specific IC analysis to other IC (the probability is close to zero).